Computer graphics systems are special purpose computers that are used to create complex images on a display and to allow the computer user to modify and store the images.
Showing images on a display and moving the images on the display screen is a complex computer task, and there is a need in the industry for methods for more efficiently performing this complex task. In addition, as computer graphics applications become more popular, there is a need in the industry for computer graphics systems that are less expensive than current systems. this complex task. In addition, as computer graphics applications become more popular, there is a need in the industry for computer graphics systems that are less expensive than current systems. Many of the elements of a typical computer graphics system are shown in FIG. 4 of U.S. Pat. No. 4,745,407, entitled "Memory Organization Apparatus and Method", issued May 17, 1988 to Costello. A graphics accelerator is a special purpose processor unit which receives graphics commands from the CPU and executes them, typically by changing information stored in the frame buffer. A frame buffer is a special purpose type of memory in which the memory locations correspond to a location, or pixel, on a color monitor, or other type of display. Devices not shown in FIG. 4 of Costello sequentially read the memory locations in the frame buffer, and cause the pixel to be lit with the appropriate intensity or color, thereby causing the image to be shown on the display.
If an application program running on a system such as that described by Costello contains drawing instructions and/or commands that specify that an image is to be "drawn" and stored in main memory, rather than the frame buffer memory, the CPU can not take advantage of the graphics processing power of the graphics system processor, because the graphics system processor does not have access to main memory. If the computer graphics system has virtual memory capability graphics system is further disadvantaged in that it cannot access virtual memory, and therefore cannot take advantage of the increased memory made available by a virtual memory system. Prior art compute graphics systems do not provide a method to efficiently interact directly with main memory, and do not provide a method for the graphics processor to access virtual memory.